An assay system is being developed in the K562 cell 1) to evaluate the effect of trans-acting elements on globin gene expression, 2) to permit the simultaneous analysis of transcriptional and translational controls on the differential expression of genes such as Beta and Gamma globin and 3) to investigate gene activation in what may be a "developmentally arrested" cell. Initially, we are attempting to use the K562 cell as a transient expression system. K562 cells have been transfected with PLTN3Bl Beta, a plasmid which contains the Beta gene, the two SV40 72bp repeats, and the SV 40 origin of replication. The total RNA has been isolated and is now being subjected to S1 analysis. If Beta specific message is found, the production of protein will be examined as well as the effect of transfected globin genes, pseudogenes, and intragenic segments on K562 globin gene expresion. To determine that the Beta gene (which is not expressed in K562 cells) is intact, Eco RI and Hind III libraries are being constructed and the cloned Beta gene will be placed into a heterologous expression system to study Beta message. To facilitate long term studies of gene expression, a TK- K562 subclone is being sought by subjecting K562 cells to increasing concentrations of bromodeoxyuridine.